Low tension ignition systems



' J. G. RUCKELSHAUS LOW TENSION IGNITION SYSTEMS Filed March 6, '1952 2Sheets-Sheet 1 INVENTOR.

JOHN G. RUCKELSHAUS ATTORNEYS Oct. 23, 1956 J. G. RUCKELSHAUS LOWTENSION IGNITION SYSTEMS 2 Sheets-Sheet 2 Filed March 6, 1952 INVENTOR.

' WWW ATTORNEYS United States Patent LOW TENSION IGNITION SYSTEMS JohnGreer Ruckelshaus, Madison, N. J. Application March 6, 1952, Serial No.275,045

Claims. (Cl. 123-148) This invention relates to low tension ignitionsystems, and more particularly to low tension ignition systems forinternal combustion engines.

It is an object of the present invention to provide a low cost shieldedignition system for internal combustion engines.

It is another object of the present invention to provide a low costignition system especially adapted for quick and easy installation inconventional internal combustion engines to suppress radiations of radiofrequency.

It is still another object of the present invention to provide a simple,inexpensive ignition system for converting a high tension ignitionsystem to a shielded, noise suppressed low tension ignition system.

It is a further object of the present invention to provide a low cost,low tension shielded ignition system which substantially eliminates thecondenser effect of high tension shielding in ignition systems therebysubstanitally increasing spark plug life and eliminating pre-ignitioncaused by premature spark discharge in high tension distributors at highaltitudes.

Still another object of the present invention is to provide distributormeans in a noise suppressed low tension system having a plurality ofconventionally mounted contacts on an insulated stator, an operablerotor, a filter device in connection with said means, and shielded lowtension leads extending from the filter and the means to each of thecoil primaries in said system. 1

Other objects and features of my invention will become apparent from thefollowing detailed description taken in conjunction with theaccompanying drawings in which:

Fig. 1 is a diagrammatic view of a preferred embodiment of theinvention;

Fig. 2 is a fragmental detail sectional view of a portion of myinvention and taken from part of Fig. 1;

Fig. 3 is a detailed sectional view of a part of my invention showing aspecial type shielded ignition coil mounted on a shielded spark plug;

Fig. 4 is a detail enlarged view of coil in coil plug, shown in Fig. 3;

Fig. 5 is a fragmental plan view taken on line 55 of Fig. 2; and,

Fig. 6 is a view taken on line 6--6 of Fig. 2.

Referring now to the drawings, wherein like numerals refer to like partsthroughout, it will be noted that a preferred embodiment of theinvention is illustrated in Figure l by way of example, in the form of aradio shielded ignition system 10 adapted to a standard four cylinder,four cycle, internal combustion engine 11, from which the conventionalplugs, coil, and high tension distributor head and rotor of thedistributor have been removed. In the form shown, the source of lowtension electrical energy is a standard 6 volt battery 12, having aterminal 13 connected with an ignition switch 14 to a filter 15consisting of an inductance 16, lead terminals 17 and 18, condensers 19and 20, mounted in a grounded shielded container 22 connected in seriesbetween switch 14 and primary lead 17. Said lead 17 is connected to2,768,227 Patented Oct. 23, 1956 ice condenser 20 and to primary coils24-27 inclusive. The filter is designed to operate on all frequenciesfrom 15 kc. to 1,000 mc., then through a shielded conductor 23 to therespective primary low voltage leads 24, 25, 26 and 27 of each of thefour ignition coils 28, 29, 30 and 31, respectively.

One primary lead of each ignition coil is connected through a shieldedconductor 32, 33, 34 and 35 respectively to a segment 32a, 33a, 34a and35a, of a low tension commutator or selector switch 36. A low tensionrotor 37 driven by distributor shaft 38 is connected to one side of apair of standard distributor points 39 and 40 in the base of thedistributor 41. The other distributor point 40 is connected to thebattery 12 through the ground" G-43 of the engine 11. A condenser 42 isconnected across contact points 39 and 40. Each ignition coil is mountedin a shielded case 44, 44a, 44b, 44c on top of shielded spark plugs 28a,29a, 30a and 31a. One side of the high voltage secondary of the coil isgrounded While the other side of said secondary is connected to the hightension terminal of said spark plugs, respectively, as shown in Fig. 1.An electrostatic shield 45, 45a, 45b and 450 between the primary andsecondary of each coil is provided and grounded, also as shown.According to the invention, engines with any number of cylinders can beso equipped by placing one coil and plug at each cylinder and using alow tension cap with a corresponding number of contacts.

Referring now more particularly to Figures 2, 5 and 6 of the drawings,there is shown a low tension distributor head 46 consisting of a metalhousing 47 which snaps onto the distributor case 36 in the same mannerthat the high tension cap is held on by clips 48 and 48a. As shown,filter 15 is attached to the low tension cap 47. A shielded cable 23carries all wires contained therein from switch 36 to a shieldedjunction box 51 from which shielded wires go to the primaries of thevarious ignition coils as shown in said Figure l. Mounted inside the lowtension cap is an insulated plate 52 as shown in Fig. 5, on which fourcontact segments 32a, 33a, 34a and 350 are mounted in a circle aroundthe shaft 38. A center contact 54 is connected by an insulated connector65 to the breaker point 39. The low tension rotor 37 is placed on theend of shaft 38 in the same manner as the high tension rotor is normallyused. This rotor consists of an insulated arm 55 in which a recess 56 ismoulded. This recess carries a contact brush 57 supported by springmember 58 in such a way that when assembled, the brush is held firmlyagainst center contact 54 and one of the segments 32a, 33a, 34a and 35a,and being in a recess the brush is rotated by the rotor arm 55 so thatit can move up and down to make good contact with the segments 32a, 33a,34a and 35a and center contact 54.

Referring now to Figures 3 and 4, I show details of one of the ignitioncoils 28 containing primary and secondary windings. Said coil is ofnovel design in that it is wound on a special type core in which thecenter leg has an air gap to store the energy for the spark discharge.This c-ore electromagnetical ly encloses both primary winding 60 andsecondary winding 61. Said windings 60 and 61 are electrostaticallyshield from each other by an unshorted turn of copper foil 52 that isgrounded. This feature is more clearly shown in Fig. 4. Further, saidelectrostatic shield is used to isolate the radio frequency set up bythe discharge of the spark at the cylinder and to prevent electrostaticcoupling back into the primary winding. Each ignition coil is encased ina metal shielded container 63 which is grounded to a shielded spark plug64 and to the shield of the conductor connecting the primary atterminals 65.

It should be noted in accordance with my invention, that all wires,coils and contacts are shielded and the shields grounded with theexception of the wire running from the filter to the battery. This doesnot need to be shielded due to the fact that all radio frequencycurrents set up within the system by either the sparking of the sparkplugpoints or the primary breaker points are filtered and conveyed toground by this filter, as hereinafter explained. V

The operation of my system disclosed herein as applied to an internalcombustion engine is as follows:

Ignition switch 14 is turned on and the engine cranked in the usualmanner. The breaker points 3) and 40 are opened and closed by cam 67 inshaft 38 and these points being in series with the low tension selectorswitch rotor 37 and contacts 32a to 35a operate in proper sequence tothe ignition coil primaries. The timing is so arranged that the standardbreaker points do all the coil firing. The selector switch 36- in thelow tension head 46 merely selects the primary to be energized. Nocurrent is ever made or broken by the selector switch. its contacts arealways closed while the standard breaker points are opening and closing.Said timing is further so arranged that contacts 39 and 40 are alwaysopen while rotor brush is travelling from one segment of the selectorswitch to another. While brush 57 is connected to a segment of theselector switch, breaker points 39 and it? close. They then open,allowing condenser 42 to discharge energizing spark coil 28 and plug 28ato which it is connected at that time. Breaker points 39 and 40 thenopen and the selector switch rotor 37 moves to another positionconnecting another spark coil primary 29 into circuit. Breaker points 39and 40 then open and close firing spark plug 29a. This operationcontinues, firing plugs 30a and 31a in proper sequence.

From the foregoing, it is apparent that there is thus provided a novelnoise suppressed ignition system in which a single standard set ofdistributor breaker points is used to time the primaries of variousignitioncoils in proper sequence thereby eliminating the need of timingeach primary separately as in other low tension systems. There is alsoprovided, according to my invention, a simple method whereby this systemcan easily and quickly be installed on engines designed for high tensionsystems with the minimum of effort so that said engine can beefficiently shielded from emitting radio interference. Furthermore, thedistributor cap, and the ignition coils are so designed that they can besupplied completely wired together by a shielded low tension conductor.The installation as indicated comprises detaching high tension cap andremoving old plugs and ignition coils. The new cap is snapped onto thedistributor base with new distributor rotor, new plugs are screwed intocylinders, ignition coils attached to the plugs and the battery leadconnected to the filter. The engine is then ready to operate and isefficiently shielded against any radio interference.

The advantages of my system over high tension shielded systems will beapparent in that it is much less costly than properly shielded hightension system. This is very important, for my system makes it possiblefor its use on installations where the cost of high tension shieldedsystems would be economically impractical. Also, my system can be easilyinstalled since it requires no special knowledge of tools. It can beinstalled in a matter of 7 minutes and no changes in the timing orsetting of the breaker points is required. Other types of shielding andsuppression equipment take skill and hours of time to install. llt willfit any conventional engine now using a high tension system.

When shielding is placed over long high tension wires, a condensereflect caused by the wire and the shield causes excessive sparking atthe plug thereby greatly reducing plug life. This condition is not foundin my present invention because all shielded wires are at low tension.

At, high altitudes, the sparking of the high tension rotor often occursearly due to the fact that the spark jumps i from the rotor to thecontacts on the distributor cap before the rotor is opposite thecontacts, thus causing pro-ignition which is highly objectionable. Thiscondition is eliminated in my system due to the fact that all switchingis done at low tension.

A most important feature of my system is its very high efiiciency toconfine all interfering radio frequency fields within the system. Inother words, where most systems create RF and then means have tobetaken. to, eliminate it, my system is designed to produce nointerference. Noise tests have been conducted on vehicles using thissystem and conducted interference and radiated interference recordedfollowing-instructions outlined in JAN- l225 joint Army and Navyspecifications. Conducted interference tests consisted of attaching awire from the output of the filter 15, Figure 1, to the antenna of aradio noise meter and readings taken at predetermined frequencies from15 kc. to 1,000 mc. Both conducted and radiated interferences were foundto be negligible over the range tested.

While the foregoing description of my system and method of eliminatingradio frequency interference have been illustrated with the use ofignition coils and battery power, they can also be used to control radiofrequency ignition systems incorporating an oscillator and radiofrequency step up transformers at each plug. In this case, instead ofpoints 39 and 40 breaking the battery current as in Fig. 1, they key theoutput of the oscillator so that radio frequency energy at low tensionis distributed to the primaries of radio frequency step up transformersmounted at the plugs instead of ignition coils. The selector switchis'connected in the same way as shown in Fig. 1.

While a preferred embodiment of my invention has been described andillustrated herein, it is to be noted that modifications as to form,arrangement of parts and use of materials may be made without departingfrom the spirit and scope of the invention as claimed.

I claim:

1. In a low tension ignition system for internal combustion engines thatmay have a standard high tension unshielded system, the improvementcomprising a source of electrical power, a low tension selector switch,a set of breaker points in electrical circuit with said selector switch,means for driving said switch, a plug for each cylinder of the engine,an ignition coil mounted at each plug adjacent to the cylinder which itfires, shielding means for isolating the radio frequency of the plug andsecondary at the cylinder, and two wire ungrounded primary circuit meansfor selecting and firing each plug in a predetermined sequence, saidimprovement being R. F. noise free and adapted for easy installation onsaid engines.

2. In an ignition system for multiple cylinder internal combustionengines, a low tension ignition harness comprising a unidirectionalsource of power, means for mounting a spark plug in close relationshipwith an ignition coil at each cylinder, said coils being provided withelectrostatic shields between their primary and secondary circuits toisolate radiated radio frequency of the secondary in each cylinder, lowtension means for selecting the primary of the coil to be used forfiring a selected plug at a given instant, breaker point meanselectrically in circuit with the selecting means and mechanicallyconnected to said selecting means, a primary filter in circuit with saidbreaker point means to isolate the radio frequency of breaker points,and a primary filter circuit, said last circuit being connected betweenthe battery in the engine and the common wire leading to each primarythrough the shielded harness.

3. Means for suppressing radio frequency interference caused by ignitionsystems of internal combustion engines, comprising a battery having agrounded terminal and an ungrounded terminal, a high tension distributorbase normally installed in an engine, shielded spark plugs, a metaldistributor cap, a distributor shaft, a low tension selector switch,said switch having segments mounted in said cap, and a rotor slidable onand rotatable by the distributor shaft, a plurality of ignition coilsmounted adjacent said spark plugs, and connected thereto by a shortshielded high tension conduit, shielded cables connecting the primariesof said coils to the segments of the selector switch, an electricalfilter connected between the primaries and ungrounded battery terminal,means whereby as the rotor engages a given segment of the selectorswitch the breaker points will fire a pre-selected spark plug through acoil attached to said plug and segment in correct firing order, saidpoints remaining open until the rotor engages another segment of saidselector switch for the firing of another plug in like manner and inproper firing order.

4. Means for suppressing radio frequency interference caused by ignitionsystems of internal combustion engines, comprising a battery having agrounded terminal and an ungrounded terminal, a high tension distributorbase normally installed in an engine, shielded spark plugs, a metaldistributor cap, a distributor shaft, a low tension selector switch,said switch having segments mounted in said cap, and a rotor slidable onand rotatable by the distributor shaft, a plurality of ignition coilsmounted adjacent said spark plugs, and connected thereto by a shortshielded high tension conduit, shielded cables connecting the primariesof said coils to the segments of the selector switch, an electricalfilter connected between the primaries and ungrounded battery terminal,means whereby as the rotor engages a given segment of the selectorswitch the breaker points will fire a pre-selected spark plug through acoil attached to said plug and segment in correct firing order, saidpoints remaining open until the rotor engages another segment of saidselector switch for the firing of another plug in like manner and inproper firing order, and means for adapting said assembly to suppressradio frequency in an engine upon which an unshielded ignition systemhas been installed without changing the timing and adjustment of thedistributor base and breaker points.

5. Compact easily replaceable and removable noise suppressing means forshielding an ignition system that may formerly have had a standardunshielded system comprising a source of electrical power, thecombination of a selector switch assembly, a plurality of ignition coilsand spark plugs each mounted on a cylinder of an internal combustionengine, said coils being connected to the switch assembly, the secondaryof each coil being electrically isolated at each cylinder, a groundedelectrostatic shield between the primary and secondary of each coil,shielded primary leads and shielded secondary leads, a high tensiondistributor base, a low tension selector switch mounted on said base, acam shaft in said internal combustion engine for operating the switch,said switch being connected to the primary leads, a two-way ungroundedelectrical circuit for one set of breaker points for timing the firingof each ignition coil primary as it is connected in circuit by saidselector switch, and primary filter circuit means connected between thebattery and common wire means for isolating the spark of said breakerpoint.

References Cited in the file of this patent UNITED STATES PATENTS1,217,484 Milton Feb. 27, 1917 2,114,189 Kronmiller Apr. 12, 19382,161,605 Yolles June 6, 1939 2,180,358 Hooven Nov. 21, 1939 2,238,915Peters et al. Apr. 22, 1941 2,240,632 Stone May 6, 1941 2,297,659 LorantSept. 29, 194-2 2,318,271 Weiche May 4, 1943 2,533,920 Crook Dec. 12,1950

